• Geosystem Engineering
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• v.21 no.6
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• pp.344-351
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• 2018

It is reported that the flooding rate in low permeability sandstones is low and the oil recovery is hard to increase after water breakthrough. Understanding characteristics of waterflood is hence important for the recovery improvement. In this work, flooding tests on low permeability sandstones were conducted. The corresponding flooding characteristics were investigated by means of CT scanning and Nuclear Magnetic Resonance. Effects of irreducible water and different rates were also discussed in detail. Experimental results reveal a piston-like displacement at a low rate in low permeability samples. The saturation profile is steep and almost vertical to the forward direction. The results at a low rate confirm that once water broke through, increasing the flooding rate or flooding time can hardly reduce the remaining oil inside the sample. It is probably due to the high pore-throat ratio proven by rate-controlled mercury. Results also confirm that the presence of initial water enhanced sweep efficiency substantially. On one hand, because water had previously occupied the small pores, the subsequent oil can only invade relatively large pores and became more movable. On the other hand, stable collars can not form due to the steep front, which may suppress the snap-off.

• Journal of Audiology & Otology
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• v.25 no.1
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• pp.8-13
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• 2021

Background and Objectives: In 2013, the Singapore government reviewed and expanded the Senior Mobility Fund (SMF) to provide subsidy for assistive devices, including hearing aids (HA). While SMF has improved accessibility to HA, its impact on HA acquisition has not been determined. The study aims to elucidate the influence of SMF on HA acquisition and the relationship between financial funding and compliance to HA use. Subjects and Methods: Retrospective review of 643 patients seen between January 2017 to January 2018 at the earnose and throat specialist outpatient clinic, who were referred for a hearing aid evaluation. Of the 643 patients, 109 patients with baseline hearing handicap (HH) scores recorded, and no formal diagnosis of cognitive impairment were included. The patients were grouped according to SMF eligibility and clinical data were obtained. Results: The odds ratio for acquiring HA was significantly higher with SMF, regardless of HH scores. When looking at actual degree of hearing loss (DHL), HA uptake was significantly higher in the least severe of DHL categories. There is no relationship between SMF and compliance to HA use. However, HH score is positively correlated with data log in regression analyses. Conclusions: SMF appears to influence HA acquisition. Especially in financially funded patients with low self-perceived HH, the benefits of HA may be underappreciated given the few hours of HA use. Further studies are warranted to investigate the impact of financial funding on outcomes of HA users to help policy planners and clinicians be prudent in the utilization of SMF.

• Korean Journal of Audiology
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• v.25 no.1
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• pp.8-13
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• 2021

Background and Objectives: In 2013, the Singapore government reviewed and expanded the Senior Mobility Fund (SMF) to provide subsidy for assistive devices, including hearing aids (HA). While SMF has improved accessibility to HA, its impact on HA acquisition has not been determined. The study aims to elucidate the influence of SMF on HA acquisition and the relationship between financial funding and compliance to HA use. Subjects and Methods: Retrospective review of 643 patients seen between January 2017 to January 2018 at the earnose and throat specialist outpatient clinic, who were referred for a hearing aid evaluation. Of the 643 patients, 109 patients with baseline hearing handicap (HH) scores recorded, and no formal diagnosis of cognitive impairment were included. The patients were grouped according to SMF eligibility and clinical data were obtained. Results: The odds ratio for acquiring HA was significantly higher with SMF, regardless of HH scores. When looking at actual degree of hearing loss (DHL), HA uptake was significantly higher in the least severe of DHL categories. There is no relationship between SMF and compliance to HA use. However, HH score is positively correlated with data log in regression analyses. Conclusions: SMF appears to influence HA acquisition. Especially in financially funded patients with low self-perceived HH, the benefits of HA may be underappreciated given the few hours of HA use. Further studies are warranted to investigate the impact of financial funding on outcomes of HA users to help policy planners and clinicians be prudent in the utilization of SMF.

• Korean Journal of Plant Taxonomy
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• v.53 no.3
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• pp.201-212
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• 2023

Parasenecio pentaphylla, a new species of the genus Parasenecio from Mt. Ilwol-san, Ilwol-myeon, Yeongyang-gun, Gyeongsangbuk-do, Korea, is described and illustrated here. In Korea, this species has been recognized as P. adenostyloides, known to be a Japanese endemic species. However, it is clearly distinguished from P. adenostyloides by its involucre shape, the number of phyllaries, the number of florets per capitulum, and the ratio of the tube length to the throat length. A molecular phylogenetic analysis using the Internal Transcribed Spacer region also clearly indicated that P. pentaphyllaria was genetically distinct from P. adenostyloides. Therefore, it is recognized as an independent species, different from P. adenostyloides. The specific epithet "pentaphyllaria" was given based on its characteristic of having five phyllaries.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.64-70
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• 2005

The overall results of hot firing tests of fuel-rich gas generator with impinging injector at design and off-design points are described. The gas generator consists of an injector head with impinging injector, a water cooled combustor wall, a turbulence ring to enhance mixing, an instrument ring measuring temperature and pressure and a nozzle. The combustion tests were successfully performed without damage of gas generator. Test results show that the outlet temperature is not dependent on residence time of hot gas within 4～6msec but dependent on chamber pressure. The relation between outlet temperature and combustion efficiency resulting from measured pressure, mass flow rate and area of nozzle throat is shown. The overall O/F ratio is the critical parameter to determine the outlet temperature and the linear correlation between two parameters is established.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.24 no.3
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• pp.1-16
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• 2011

Objective : In the theory of Korean medicine, Scrophulariae Radix (SR) can clear away heat and cool the blood, nourish yin and promote the production of the body fluids, relieve toxin and benefit the throat. The present study was carried out to investigate effects of SR on allergic contact dermatitis (ACD) induced by 2,4-dinitrochlorobenzene (DNCB) in mice. Methods : In this experiment, effects of SR on clinical aspects on the skin, histopathological changes such as spongiosis, mast cell distribution, immune cell infiltration in tissue, spleen / body ratio and production levels of serum cytokines were investigated in vivo. In addition, effects on cell viability and release of b-hexosaminidase and histamine were also investigated in vitro. Results : SR treatment diminished erythema, desquamation and keratosis which were induced by repeated painting of DNCB. Spongiosis and edema were diminished by painting of SR in histopathological observation, infiltrations of mast cell and monocytes were also decreased in SR group. In addition, spleen / body ratio was lowered compared to ADC control group. Production level of IFN-${\gamma}$ in serum was decreased, but level of IL-4 did not affected by SR. Finally, more than 400 ${\mu}g/ml$ of SR treatment groups showed decreased cell viabilities in RBL-2H3 cells. Treatment with over 200 ${\mu}g/ml$ of SR decreased b-hexosaminidase release, and treatment with over 400 ${\mu}g/ml$ decreased histamine release in vitro. Conclusion : these data suggest that SR can decrease symptoms of ACD, then SR is useful to treat patient with ACD.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.156-160
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• 2007

Ejector system is a device to transport a low-pressure secondary flow by using a high-pressure primary flow. Ejector system is, in general, composed of a primary nozzle, a mixing section, a casing part for suction of secondary flow and a diffuser. It can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejector system is simple in construction and has no moving parts, so it can not only compress and transport a massive capacity of fluid without trouble, but also has little need for maintenance. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an applicable model and operating conditions for an ejector in the condition of sonic and subsonic, which can be extended to the hydrogen fuel cell vehicle. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Optimization technique and numerical simulation was adopted for an optimal geometry design and satisfying the required performance at design point of ejector for hydrogen recirculation. Also, some sonic and subsonic ejectors with the function of changing nozzle position were manufactured precisely and tested for the comparison with the calculation results.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.1-9
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• 2017

Numerical computations are performed to investigate the effect of pintle stroke on the performance of an internal pintle thruster. Results show that the thrust control ratio was less than 2% and the aerodynamic load ratio was 22% as the pintle stroke increased. The flow past the nozzle throat rapidly expanding because of the shape of the pintle, and a shock wave was generated. Particularly, at the pintle stroke distance of 4 and 5 mm, the shock wave hit the wall of the nozzle, results in peeling bubbles. Depending on the altitude, the thrust increased and the aerodynamic load decreased, but the difference was as small as 1.5%. In the presence of the bore, the reduction of the pintle tip area resulted in a decrease in aerodynamic load.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.81-88
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• 2013

The component based propulsion modeling and simulation of an dual ramjet engine using Taylor-Maccoll flow equation and quasi 1-D combustor model. The subsonic and supersonic intake were modeled with Taylor-Maccoll flow having $25^{\circ}$ cone angle, the gas generator which transfers a pre-combustion gas into supersonic combustor was developed using Lumped model, and the determination of the size of nozzle throat of a gas generator was described. A quasi 1-D model was applied to model a supersonic combustor and the variation of temperature and pressure inside combustor were presented. Furthermore, the thrust and specific impulse applying fuel regulation by pressure recovery ratio and equivalence ratio were derived.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.1
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• pp.1-12
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• 1998

Industrial ejector system is a facility to transport, to compress or to pump out a low pressure secondary flow by using a high pressure primary flow. An advantage of the ejector system is in its geometrical simplicity, not having any moving part, compared with other fluid machinery. Most of the previous works have been performed experimentally and analytically. The obtained data. are too insufficient to improve our current understanding on the detailed flow field inside the ejector. In order to provide more comprehensive data on this ejector flow field, two-dimensional computations using Reynolds-averaged Navier-Stokes equations were performed for a very wide range of operating pressure ratio of the supersonic ejector with a secondary throat. The current results showed that the supersonic ejector system has an optimum pressure ratio for the secondary flow total pressure to be minimized. The numerical results clearly revealed the shock system, shock/boundary layer interaction, and secondary flow entrainment inside the supersonic ejector.